None.
Not Applicable.
This invention relates to the manufacturing and assembly of movable sockets, for example, ball-joints as used in automotive steering and suspension systems, and more particularly, to a method and device for performing the operation of closing one end of a movable socket without spinning, swaging, or welding, by means of an expanding solid cover-plate. While the invention is described in detail with respect to automotive applications, those skilled in the art will recognize the broader applicability of the invention.
Conventional ball-joints, and other movable sockets are used, for example, in automotive steering and suspension applications. The sockets comprise a housing having a circular cylindrical internal surface, a ball stud with a ball head contained in the housing, and a synthetic resin, heat treated steel, or sintered alloy bearing member supporting the ball head within the housing. These components are installed into the housing through a posterior opening, with the ball stud extending outward through an axially disposed anterior opening of a smaller diameter than the ball head. Traditionally, the posterior opening is closed by means of a cover-plate, which is spun or swaged in place, as seen in FIGS. 1A-1D. Alternatively, the cover-plate may be welded into place.
Cover-plate elements are traditionally formed from a stamping process, whereby individual components having desired dimensions are stamped from metal sheets. Either during the stamping process or in a subsequent manufacturing step, a raised boss may be drawn or stamped into the cover-plate, and a centrally located hole of predetermined dimensions punched therein to receive a self-tapping or threaded grease fitting.
Once secured in place, the cover-plate presses on the bearing member either directly or indirectly through a resilient rubber intermediate component and a pressure plate.
Bearing components within the housing, against which the ball head or moveable component is articulated, perform best when the housing material is fully hardened, as it is better able to withstand the stresses and frictional wear associated with movement of the bearing components. Accordingly, the use of hardened materials greatly extends the useful life of the bearing components and the housing. However, hardened material surfaces greatly hinder traditional spinning, swaging, or welding operations required to enclose the housing.
Once assembled, movable sockets may be utilized as load carrying members in numerous mechanical systems, including automotive vehicle suspension and steering systems. Obviously, movable sockets or ball-joints employed in these applications are subjected to various operating conditions, and may be required to carry substantial loads. When wear develops, the performance of the movable socket or ball-joint degrades and, in the case of automotive applications, may result in erratic steering or excessive looseness and play in the vehicle suspension system.
As described in U.S. Pat. No. 6,202,280 B1, (herein incorporated by reference) a method and device for expanding a conical or convex cover-plate within the posterior opening may be employed to secure and enclose the socket components within the socket housing, allowing for closure of a fully hardened housing without the need for traditional spinning, swaging, or welding operations.
Alternatively, as is described in U.S. Pat. No. 6,125,541 to Parker, herein incorporated by reference, a two-stage ram having first and second contact surfaces may be utilized to first expand a conical or convex wear-indicator style cover-plate, having an axial opening, within the posterior opening of a housing, and then to further deform the cover-plate to a predetermined final position relative to the internal components of the socket to provide a predetermined wear indicator distance.
Similarly, as is described in co-pending U.S. Patent application Ser. No. 09/681,305, herein incorporated by reference, a two-stage ram having a contact surface and a concentric pivot punch may be brought into engagement with the cover-plate within the posterior opening of a housing for the purpose of closing the housing. Pressure exerted by the two-stage ram is transferred to the cover-plate through the contact surface, expanding the cover-plate to conform to the contact surface and enclosing the internal components within the socket housing. The exerted pressure additionally results in the extension of the concentric pivot punch into the central orifice of the cover-plate, controlling the expansion of the cover-plate and establishing the central orifice to predetermined dimensions upon closure of the socket housing.
Each of the aforementioned devices and methods for closing a movable socket with a ram requires that the cover-plate incorporate an axial opening to permit the desired deformation under load from the ram. However, some socket designs require a sealed or closed cover-plate having no axial opening. Such socket designs still utilize hardened housings, and therefore still have the same housing hardness issues as stated above. In many such applications, the socket is lubricated only prior to the assembly process, and is not lubricated after assembly. These are often referred to as xe2x80x9clubed for lifexe2x80x9d sockets. The socket closure devices and techniques previously described to overcome the housing hardness issues cannot be utilized with such xe2x80x9clubed for lifexe2x80x9d sockets, as cover-plates without axial openings will not properly deform under load from the ram, and accordingly, will not result in ideal socket closure.
Accordingly, it is highly advantageous to develop a ram device capable of expanding a solid conical or convex cover-plate within a socket housing to enclose the housing without the need for specialized spinning, swaging, or welding operations.
Briefly stated, a first aspect of the present invention provides an expanding solid cover plate for closing one end of a movable socket. The expanding solid cover plate incorporates either an upper or lower circumferential groove to control and direct deformation of the solid cover-plate during an expansion process resulting in the solid-cover plate engaging and closing one end of a movable socket.
A second aspect of the present invention provides a ram stop-out plate configured to engage an expanding solid cover plate having either an upper or lower circumferential groove, and for directing an applied force to the solid cover plate, whereby the cover plate is deformed and expanded to close one end of a movable socket.
A third aspect of the present invention features an assembly technique for enclosing an open end of a movable socket comprised of fully hardened materials with an expanding solid cover-plate having a circumferential groove on either an upper or lower surface. During assembly, various internal components of the movable socket are installed within a housing through a posterior opening and a solid conical or convex cover-plate having a circumferential groove on either an upper or lower surface is positioned over the components within the posterior opening. A ram of the present invention having a contact surface is brought into engagement with the solid cover-plate. Pressure exerted by the ram is transferred to the cover-plate through the contact surface, deforming and expanding the cover-plate to close the socket housing.
A fourth aspect of the present invention is an assembly technique for enclosing an open end of a movable socket comprised of fully hardened materials with an expanding solid cover-plate so as to force a quantity of lubricant material to flow though the movable socket assembly during the closure process. Forcing the flow of lubricant through the socket assembly eliminates the need to pre-lubricate individual components prior to placement in the socket assembly.
The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.